The present invention relates to an aqueous acid electroplating bath for producing extremely bright electrodeposits of tin. Additionally, the present invention relates to a brightening agent and an acid plating bath containing the brightening agent which produces brighter deposits at higher current densities and with less pitting than with previously known tin plating baths over a very broad current-density range.
In the field of tin brightening compositions for acid tin baths, various aromatic aldehydes and ketones compounds have been utilized. Generally, although many of these such compounds produce an acceptable plating, often it was difficult to avoid pitting as well as to obtain an extremely bright electrodeposit at high current densities.
Plating baths and plating additives heretofore utilized include those set forth in U.S. Pat. No. 3,808,277 to Alvarez; U.S. Pat. No. 3,755,096 to Passal; U.S. Pat. No. 3,875,029 to Rosenberg et al; and, U.S. Pat. No. 3,977,949 to Rosenberg. However, none of these plating baths or tin brighteners are pertinent to the present invention.